Functions of several low pressure circuits in hydraulic system of hydraulic excavator
1. Back pressure oil circuit: the low-pressure oil generated by the back valve on the system circuit replenishes oil to the low oil chamber of the hydraulic motor through the two-way oil replenishment valve when braking or overspeed suction occurs, so as to ensure that the roller is always close to the surface of the guide rail, so that the motor works stably and has reliable braking performance.
2. Drainage and irrigation oil circuit: introduce the low-pressure oil into the hydraulic motor housing after pressure reduction through the throttle valve, so that a certain amount of circulating oil can be maintained in the object even when the motor is not running. The purpose is: first, to wash the wear in the motor housing frequently. The second is to preheat the motor to prevent the motor from blocking or seizing due to uneven local thermal expansion caused by precise matching of oil distribution shaft and plunger pair after the working oil with higher temperature is introduced from the main oil circuit when the external temperature is too low, that is, the so-called thermal shock.
3. There is no back pressure in the leakage oil circuit: collect the internal oil leakage of the multi-way valve and the hydraulic motor with the oil pipe and lead it back to the oil tank through the oil filter to reduce external leakage. The return oil circuit of the hydraulic system flows back to the oil tank after passing through the air-cooled cooler and oil filter to cool and filter the return oil, so as to ensure that the oil temperature in the oil tank does not exceed 80 ℃ under the continuous working state of the excavator.
